Method and apparatus for small wheel disc brake

ABSTRACT

An improved small wheel disc brake for skateboards, scooters, and carts, which facilitates a heat management design to provide higher level of performance operation without brake failure thereby improving the safety of said vehicles. The disc brake ( 6 ) includes a non-metallic friction pad disc ( 18 ) which is fixed to the central aperture of a wheel hub ( 28 ), (FIG.  1 ) and a matching non-turning rotor ( 24 ) that is slideable linked to a hub ( 16 ) that is made apart of an axle support structure ( 17 ). The non-turning rotor ( 24 ) is controllably coupled with the friction pad disc ( 18 ) by means of cam levelr ( 13 ), which is a pivotally attached to the axle support structure ( 17 ) by an attachment bolt ( 15 ). A means is provided for remotely activating the mechanism, which includes a Bowden cable ( 8 ), wire ( 9 ) and handgrip ( 10 ). The friction pad disc ( 18 ) provides for efficient brake action and smooth modulation while insulating wheel components from frictional heat associated with braking. The non-turning rotor ( 24 ) conducts frictional heat directly into said axle support structure ( 17 ), which provides for rapid dissipation of heat by means of air-cooling.

This is a continuation in part of Application Ser. No. 09/505,798 filedFeb. 17, 2000 now abandoned.

FIELD OF THE INVENTION

The invention relates to a brake device for small-wheeled vehicles suchas skateboards, scooters, small carts and the like. The brake can beactuated by a mechanical or hydraulic system and activated by means of aremote actuator.

DESCRIPTION OF THE PRIOR ART

Over the past 50 years inventors have developed a variety of brakesystems for small-wheeled vehicles. They range from the very crude stickinto the ground to a finely designed hydraulic system featuring a remotehandgrip. Prior art presented has proven adequate for operation bychildren and adults at relatively slow speeds. However, prior art doesnot provide a brake mechanism that will withstand self-generated heatforces when operated by an adult rider at speeds exceeding 15 mph forany length greater that ¼ mile with a downhill inclination greater than4 degrees. The problem lies within frictional heat generated by a brakemechanism when trying to stop an adult rider traveling under the forceof gravity over a period of time.

The force required to slow or stop a rider on a wheeled vehicle isdependent upon the weight and velocity of the rider, and the angle ofinclination of the run. Increasing any of these heel variables increasesthe amount of force required to stow the rider. The consequence of usingfrictional force to slow a vehicle is heat generation. As a ridertravels downhill and applies brake pressure in order to control speed,frictional heat continually builds into the brake mechanism. Consideringthis heat is localized to the surface area of a small wheel, the amountof heat can be substantial

Testing has shown that during normal recreational use a 180 pound ridertraveling on a skateboard equipped with a brake at 15-20 mph for adistance of ½ mile with a downhill inclination of 4-6 degrees willgenerate brake temperatures between 250° F. and 350° F. Larger riderstraveling a longer distance, such as a mile, can generate braketemperatures in excess of 500° F. Urethane and rubber wheels are heatsensitive and will soften to a point of deformation at a temperature of225° F. As temperatures rise to 300° F. wheels lose the resilientintegrity required to maintain their form and can no longer support therider. Given the use of small-wheeled vehicles by adult riders, heatgenerated by the brake must be given design consideration to provide forsafe, reliable operation over prolonged use.

The invention disclosed was developed over a period of several years bytesting various methods for braking small wheel vehicles such asskateboards and small carts. Methods that were tested include dragbrakes of various designs, and mechanisms that apply frictional pressureto the wheel surface, The drag brake proved ineffective at deliveringenough braking force to slow an adult rider at speeds in excess of 15mph. A variety of mechanisms were devised tat applied frictionalpressure directly to the wheel surface. These mechanisms proved to beineffective due to heat build up at the wheel. During operation,frictional heat would melt wheels leaving the rider in a perilouscondition. Therefore, it became apparent that the materials used toresist frictional force were just as important as the application offorce itself. For our application, a mechanism needs to provide enoughbraking force to slow a small wheeled vehicle carrying an adult rider atspeeds in excess of 40 mph without melting the wheels or damaging thebrake mechanism. The following is a list of desired operationalspecifications:

1) The brake needs to be readily adaptable to common wheel axles andcommercially available small wheels.

2) The brake must operate to a rider's expectations. Specifically, thebrake should operate in a smooth and reliable manner over a minimaldistance of at least a mile while traveling downhill at w s ranging from0-40 mph. An adult rider would be defined as a body having a weight ofapproximately 180 pounds.

3) The mechanism is preferably hand operated to provide a well regulatedand smooth slowing of the vehicle. Hand operation leaves riders feetunencumbered to provide for maximum stability and control.

4) The brake has to effectively transfer frictional heat, generatedduring operation, away from heat sensitive wheel hubs and tires and intoan axle support structure that will not be damaged by thermal loading.Heat must then be effectively convected away from this structure toprovide cooling for the brake.

5) The brake must provide thermal insulation for wheels for maximumdurability.

6) The brake mechanism must be scaleable to accommodate different sizewheels, axles, vehicles riders, hills and performance needs.

7) The mechanism would need to be of a reliable, durable, unobtrusivedesign that is easy to maintain and repair.

The brake mechanism described herein has been extensively tested on avariety of vehicles, under a variety of operational conditions and hasachieved all of the above operational specifications.

Prior art has not provided design consideration for frictional heatgenerated during brake operation. An example of this is found in U.S.Pat. No. 4,076,266 to Krausz (1978). The Krausz art provides a brakemechanism that utilizes a piston that seats a friction member at it'send, which bears against a brake disc fitted to the inside face of awheel. When activated, the friction member is brought into contact withthe spinning brake disc, which is in direct contact with the wheel. Shefriction member is intrinsically non-conductive and therefore stopsfrictional heat from entering the axle support structure. Therefore, asa rider travels downhill and frictional force is applied to the wheel,frictional heat loads directly into the brake discs and then into thewheels. When the brake disc and wheel reaches a temperature of 225° F.the wheel begins to soften to a point of deformation and starts to melt.The Krausz art does not provide for a place for heat to move into apartfrom the brake disc and wheel. Krausz did not recognize heat as being anissue of concern as evidenced by the use of the friction member and lackof mention within the art

In addition, the Krausz art specifies the fiction member to be limitedin size to the diameter of the engaging piston. This limitation does notprovide adequate frictional surface area to effect braking forcenecessary to stop an adult rider traveling under the influence ofgravity at any speed greater than 10-15 mph.

In addition, the Krausz art specifies the piston to provide frictionalforce offset from the axle. This provides an unequal force upon thebrake disc and wheel, which tends to bend the axle. This design problemleads to excessive wear of the brake disc, moving additional frictionheat into the brake disc and wheel. The Krausz art would not beconsidered safe for operation by anyone other than a small child at avery slow speed. Another example is discussed within U.S. Pat. No.4,295,547 to Dungan. The Dungan art describes two separate means ofbraking a small wheel vehicle. In both instances the art provides for afriction member to apply frictional pressure to a disc attached to thewheel face, whereby isolating frictional heat from the axle supportstructure. Frictional heat generated during brake operation is directedinto the brake discs and the wheel face, as does the Krausz art. TheDungan art provides for an annular friction member, which is animprovement over the Krausz art, however, Dungan, like Krausz does notprovide design consideration for frictional heat generated duringoperation. During normal operational use, frictional heat is directedinto the wheels until such time as the wheel temperature reaches 225°F., and begins to melt, placing a rider in a dangerous situation. Thistemperature can be reached within a distance of 100 feet. In addition,proper design of a small wheel brake involves not only making provisionto insulate the wheels from frictional heat, but also to provide alocation for heat to reside that will not be damaged by thermal loading.This location should be able to withstand temperatures exceeding 500° F.and provide for ideal convection of heat into the air.

Given the high performance nature of existing vehicles, miles of openterrain and the growing popularity of Gravity Games and Extreme Games,riders are traveling faster and further than ever on vehicles without areliable means of braking or slowing. Small wheel vehicle enthusiastsare injuring themselves due to the lack of brake mechanism that willwithstand self-generated heat over a reasonable distance of operationwithout brake failure.

Clearly, the invention presented herein provides many advantages overthe prior art noted above. The treatment of the large amount ofgenerated heat from friction based braking systems stands as theparamount issue in small wheeled brake systems. Urethane and rubberwheels melt at substantially lower temperatures than the other metalcomponents. Surprisingly, prior art noted above focuses heat created inthe braking process directly on the wheel, the most heat sensitivecomponent of the brake. No consideration has been provided forfrictional heat or the consequences of wheel melt down when used by anadult rider at a modest speed. Prior art can only be considered safewhen operated by small children or adults at very low speeds.

OBJECTS AND ADVANTAGES

The most fundamental objects and advantages of the invention are:

a) to provide a brake mechanism that effectively transforms kineticenergy from spinning wheels into heat and then moves that heat to aplace that will not be damaged by thermal loading;

b) to utilize a new method for braking small wheel vehicles whereby aheat resistant friction pad disc is made a part of the inside face of awheel hub and is used to insulate the wheel from frictional heatgenerated during the brake process;

c) to utilize a new method for braking small-wheel vehicles thatincludes a non-turning rotor that is mounted facing and substantiallymatching the friction pad disc;

d) to utilize a new method of braking small wheel vehicles whereby thenon-turning rotor affects braking forces and conducts heat generatedduring brake operation into itself;

e) to utilize a new method for braking small-wheel vehicles wherebyfrictional heat generated during brake operation is conducted into thenon-turning rotor and axle support structure;

f) to provide a brake mechanism that includes an axle and supportstructure able to withstand temperatures within a range of 250° F.-500°F. and safely convect that heat into the air,

g) to provide a brake mechanism whereby said axle support structureincludes a square hub located at it's end, centered along the axle;

h) to provide a brake mechanism whereby said non-turning rotor ismechanically linked to an axle support structure by a square hub;

i) to provide a brake mechanism whereby said axle support structureincludes an axle that extends outward from the hub, of sufficient sizeand length to support at least one wheel;

j) to provide a brake mechanism whereby the axle support structureprovides linear movement for said non turning rotor when activated by amechanical or hydraulic system;

k) to provide a brake mechanism whereby the non-turning rotor appliesequilateral pressure to the friction pad disc and wheel assemblyaffecting brake action;

l) to provide a brake mechanism that includes a cam lever of sufficientlength to provide equilateral leverage force upon the non tuning rotorat equal but opposite axis points;

m) to provide a brake mechanism that may include an arm extensionattached to the cam lever for the purpose of adjusting the Bowden cableattachment location;

n) to provide a brake mechanism that includes a wheel, wheel hubassembly and means for securing said wheel hub assembly to the axlesupport structure;

o) to provide a disc brake mechanism that may be activated by a varietyof means including a Bowden cable and wire, or a hydraulic system ormechanical linkage;

p) to provide a brake mechanism that may be used for one or more wheelsof a vehicle;

q) to provide a disc brake mechanism whereby wheels may be activateddependently of one another and receive equal braking pressure;

r) to provide a disc brake mechanism whereby brakes may be activatedindependently of one another;

s) to provide a disc brake mechanism with returns to a normallynon-activated position by means of a spring;

t) to provide a disc brake mechanism that is actuated by a foot or handlever;

u) to provide a disc brake system whereby one or more mechanisms may beactivated in unison from a single brake actuator;

v) to provide a mechanism that is readily adaptable for small vehiclessuch as skateboards, scooters and small carts;

Further advantages of the brake mechanism disclosed include; the abilityto retrofit common skateboard trucks, scooters and carts with a discbrake system that will provide riders of all sizes with a high level ofsafety and brake performance. Further objects and advantages will becomeapparent from a consideration of the ensuing description and drawings.

SUMMARY, RAMIFICATION AND SCOPE

The disc brake mechanism provided herein offers riders a new level ofbrake technology for small wheel vehicles that hereto now has not beenavailable. The brake mechanism is designed with components that willproduce and withstand braking forces necessary for slowing or stoppingan adult rider traveling at speeds in excess of 50 miles per hour.Frictional heat generated during the brake process is conducted awayfrom heat sensitive wheel components and directed into the axle supportstructure where it is safely dissipated into the air.

A notable feature of the brake is the use and location of a non-metallicfriction pad disc, which is fixed to the central aperture of the wheelhub. Locating the friction pad disc on the wheel hub provides anunobstructed path for heat to naturally move into the non-turning rotorand axle support structure.

Furthermore, the friction pad disc embodies other advantages in that:

it is porous and thereby adheres well to the wheel hub or a fixturewhich is attached to the wheel hub by a heat resistant epoxy adhesive;

it is nonconductive, thereby providing thermal insulation for the wheelhub;

it is constructed of a durable, light weight, heat resistant material;

it provides for a large braking surface area;

it is designed to operate under conditions being imposed;

it spins with the wheel, which provides for added cooling;

it may be inset into the wheel hub making it unobtrusive;

it provides riders with a smooth brake modulation;

it is readily available in a variety of formulations and densities.

The brake mechanism has numerous advantages over prior art including; anatural heat management system which helps to maintain the integrity ofthe wheels, a large friction pad surface area which provides forefficient long lasting operation, and smooth predictable modulation forthe rider. The brake has few moving parts, is compact by design and iscost effective to manufacture. The brake is readily adaptable toexisting skateboard trucks, scooters, skates and carts. The mechanismmay be operated as a stand-alone unit or may be connected to multiplebrake assemblies with a simple Bowden cable and wire assembly.

The disc brake presented herein will provide gravity sport enthusiastswit a superior means of controlling and stopping their vehicles. Thereare many areas, roads, trails and slopes that are ideal for downhillrecreation, that hereto now would be considered to be too dangerous toride because of the degree of inclination and lack of means for slowingdown or stopping. The brake presented herein will provide riders of allage and sizes with reliable speed control necessary to safely navigateand play in these areas for a great new form of recreation.

Although the description above contains many specifics, these should notbe construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a skateboard with an embodiment of the discbrake mechanism.

FIG. 2 is a plan view of the disc brake mechanism.

FIG. 3 is a view from above showing the disc brake assembly in anon-actuated configuration.

FIG. 4 is a view from above showing the brake assembly in an actuatedconfiguration.

REFERENCE NUMERALS IN DRAWINGS Number Description Number Description 1Conventional skateboard 2 Left disc brake 3 Right disc brake 4 Deck 5Front truck 6 Dual action disc brake 7 Wheel 8 Bowden cable 9 Wire 10Handgrip 11 Spring 12 Arm extension 13 Cam lever 14 Pivot hinge 15Attachment bolt 16 Square hub 17 Axle support structure 18 Friction paddisc 19 Heat Resistant Adhesive 20 Frictionless bearing 21 Axle 22 Nut23 Mounting plate 24 Non-turning rotor 25 Cable stop 26 Wire attachmentfastener 27 Bearing spacer 28 Wheel hub

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The disc brake mechanism presented herein can be adapted for a varietyof small wheel vehicles. For reason of explanation, a standardskateboard truck is illustrated using two embodiments of the brakedisclosed The two embodiments are referred to as a dual-action discbrake. Referring to FIG. 1, a conventional skateboard 1 is shown thatincludes: a deck 4, a dual-action disc brake 6, coaxial wheels 7, and ameans for the rider to remotely activate the brake using a Bowden cablesystem 8, and handgrip 10. The board operates, as does a standardskateboard with the exception that the rider holds a hand lever 10 toremotely activate the brake 6 when desiring to slow down or stop. InFIG. 3 the dual-action disc brake 6 is shown in a normally non-actuatedconfiguration. wheels 7, which include friction pad discs 18, spinfreely from non-turning rotors in this configuration. In FIG. 4 thedual-action disc brake 6 is shown in an activated configuration. A rideractivates the brake 6 by squeezing the handgrip 10, which draws a wire 9into the cable sheath 8. This action causes cam levers 13 to be pulledtogether with equal pressure at pivot hinges 14 providing an equal,leveraged force upon slideable, non-turning rotors 24. As non-turningrotors 24 become frictionally engaged with friction pad disc's 18, brakeaction is provided relative to the amount of force applied to hand grip10. The spring 11 returns and maintains the mechanism in a normallynon-actuated configuration as illustrated in FIG. 3. In FIG. 2, thedual-action disc brake mechanism 6 is shown in a non-activatedconfiguration. Each disc brake mechanism 2, 3 includes a hub 16, whichis made apart of an axle support structure 17. The hub 16 provides ameans for mechanically linking the non-turning rotor 24 to the axlesupport structure 17 while allowing for slideable movement of thenon-turning rotor 24. There are a variety of means for lining thenon-turning rotor 24 to the axle support structure 17 including: asquare hub 16 shown, or a splined shaft, or an irregular shaped shaftnot shown. The square hub 16 is located on each end of the axle supportstructure 17 at the central axis of the axle 21, The non-turning rotor24 includes a borehole matching that of the square hub 16 at its centralaperture, thus providing a linear movement along the square hub 16. Inaddition, the non-turning rotor, or section thereof 24 is formed tomatch the diameter of the friction pad disc 18. This provides for idealbrake performance, modulation and heat conduction during brakeoperation. The non-tuning rotor 24 may be leveraged into the frictionpad disc by a variety of means including a cam lever 13 shown, or arotary screw, or a hydraulic actuator, or mechanical linkage not shown.The cam lever 13 is pivotally attached to the hub 16 by an attachmentbolt 15 and pivot hinge 14, which is attached to one side of hub 16. Thecam lever 13 is forked at one end to provide equilateral pressure on thenon-turning rotor 24 when activated by the rider. The cam lever 13provides a leverage force on the non-turning rotor 24 causing it tobecome controllably engaged with the friction pad disc 18 and wheel 7.The end of cam lever 13 is provided with a means for connecting an armextension 12 or cable wire 9. Extending or reducing the length of thecam lever 13 will adjust leverage force available to riders.

Extending out from each end of the axle support structure 17 is awheel-bearing axle 21. The axle supports a wheel assembly which includesa wheel hub 28, wheel 7, frictionless bearings 20, bearing spacer 27,and friction pad disc 18 which is fixed to the central aperture of wheelhub 28. The friction pad disc 18 is formed of a non-conductivecommercial grade friction material and may be affixed using a heatresistant epoxy adhesive 19 common to the automotive industry.

The mechanism may be activated by a variety of means including a Bowdencable 8 and wire 9 as shown, a hydraulic system or a mechanical linkagesystem not shown. Referring now to the cable system shown, a Bowdencable 8 of the type having an outer sheath with a sliding wire cable 9,which is operated by means of a handgrip 10, (FIG. 1) which causes awire 9, to be retracted into the sheath 8 when handgrip 10 is squeezed.The sheath terminates at cable stop 25, which is made apart of armextension 12. The arm extension 12 is attached to cam lever 13 byattachment bolt 15. The cable wire 9 passes threw a bore in the cablestop 25, spring 11, and a bore in wire attachment fastener 26, securingthe cable to cam lever 13.

When activated, cam levers 13 apply equilateral pressure against thenon-tuning rotors 24 causing them to become controllably coupled withfriction pad discs 18. The pressure against the non-turning rotors 24applies an outward force on the wheel hubs 28, wheels 7, frictionlessbearings 20, spacers 27 and nuts 22. The wheel hub 28, bearings 20, andspacers 27 are firmly secured to the axle support structure and resistthis force by nuts 22 located at each end of the axle. The axle supportstructure 17, which includes square hubs 16, non-turning rotors 24, andmounting plate 23 resists rotational forces imposed from the frictionpad discs 18, spinning wheels 7, and any given load.

The friction pad disc 18 is made from a non-conductive material and istherefore less conductive than the metallic non-turning rotors 24.Therefore, heat generated during the brake operation is naturally drawnaway from the wheels and into the very conductive axle support structure17 where it is dissipated into the passing air. A further level ofinsulation and heat dissipation is provided by the spinning wheels.

I claim:
 1. A disc brake mechanism for small-wheeled vehicles comprising: a carriage that has an axle support structure with wheels mounted thereon that rotate freely and indent of one another so that said carriage can roll upon a surface; a heat-resistant, friction pad disc that is fixed to the central aperture of a wheel hub and which rotates with said wheels; a non-turning, heat-conductive rotor mounted to an axle support structure, wherein said non-turning rotor is controllably coupled with said friction pad disc to provide braking action; means for exerting a force upon said non-turning rotor to engage said friction pad disc; means for remotely act said disc brake mechanism; a spring for maintaining said brake mechanism in a non-activated configuration; wherein said non-turning rotor and said friction pad disc are not in engagement; wherein upon activation of said brake mechanism, frictional heat generated during braking operation is directed from said non-turning rotor into said axle support structure by conduction for dissipation, in of into the heat sensitive wheel components.
 2. The disc brake mechanism of claim 1, wherein said non-turning rotor is formed to match said friction pad disc.
 3. The disc brake mechanism of claim 1, wherein said non-turning rotor is slideably linked to said axle support structure by a variety of means including a square hub, a splined shaft or an irregular shaped shaft.
 4. The disc brake mechanism of claim 1, wherein said non-turning rotor has a central aperture or borehole having a mechanical link to provide slideable movement along said axle support structure.
 5. The disc brake mechanism of claim 1, wherein said non-turning rotor is slideably coupled with said friction pad disc by a variety of means including a cam lever, a rotary screw, a hydraulic actuator or a mechanical linkage.
 6. The disc brake mechanism of claim 1, wherein said brake mechanism is remotely activated by a variety of means including a Bowden cable assembly, or a hydraulic system or mechanical link initiated by a handgrip or foot activation.
 7. The disc brake mechanism of claim 1, wherein said friction pad disc provides thermal insulation for said wheel components during braking operations.
 8. The disc brake mechanism of claim 1, wherein said non-turning rotor conducts frictional heat directly into said axle support structure providing rapid dissipation of heat by means of air cooling over the surface area of said axle support structure. 